| As a kind of clean energy,solar energy is widely developed and utilized by human beings.Organic-inorganic hybrid metal halide perovskite solar cell,as one of the devices for solar photoelectric conversion,has become the focus of attention because of its advantages of simple preparation,low cost and high efficiency.At present,the efficiency of single-junction perovskite solar cells has reached 25.7%.Among them,titanium dioxide(TiO2)is widely used as the electron transport layer(ETL)of perovskite solar cells because of its appropriate band gap,which plays a role in blocking holes and transporting charges.In perovskite solar cells,(TiO2)ETL is usually prepared by sol-gel spin coating method,and it needs to be annealed at about 500℃ to achieve the best performance of perovskite solar cells,which limits the development of flexible devices.In addition,the stability of perovskite solar cells is also facing great challenges.As a traditional photovoltaic conversion layer,methylammonium lead iodide(CH3NH3PbI3,MAPbI3)has poor water-oxygen stability,and it is easy to decompose.The decomposed products will react chemically with the surface of(TiO2)ETL,resulting in degradation of cells performance.Therefore,it is urgent to develop a preparation method at room temperature to obtain(TiO2)ETL with excellent performance and to prolong the service life of perovskite solar cells.Considering the preparation of(TiO2)ETL with excellent performance at all room temperature and the improvement of the stability of perovskite solar cells,this dissertation has carried out the following research:1.(TiO2)DC-PMSETL was prepared by DC pulsed magnetron sputtering(DC-PMS)at room temperature,and TiO2(500℃)prepared by sol-gel spin-coating method as reference ETL((TiO2)Sol-gelETL).According to the characterization of the prepared(TiO2)ETL,it is found that the(TiO2)DC-PMSETL is mainly composed of nano-sized Anatase phase TiO2 crystal nuclei arranged along the vertical direction of the(TiO2)DC-PMSETL,forming a chain structure that runs through the whole(TiO2)DC-PMSETL.The chain structure makes(TiO2)ETL obtain high surface potential,which is beneficial to electron injection.In addition,electrons can be transported to the external circuit in the shortest path along the fiber like structure that runs through the whole ETL.The maximum energy conversion efficiency(PCE)of the planar perovskite solar cell prepared by using(TiO2)DC-PMSETL as ETL and traditional MAPbI3 as perovskite photovoltaic conversion layer is 16.1%,which is about 3%higher than that of the reference device.In addition,the hysteresis of perovskite solar cells based on(TiO2)DC-PMSETL is also suppressed.2.With the method of ion beam implantation,high-purity NH3 and CH4 were ionized by AE-38CM Kaufman linear ion source to generate low-energy NHx+and CHx+ions/groups,which were implanted into(TiO2)ETL to simulate the chemical reaction between NHx+and CHx+ions/groups and the surface of(TiO2)ETL and its influence on the performance of MAPbI3-based PSCs devices.The results show that the NHx+and CHx+ion beams implantation has a negative impact on the(TiO2)ETL performance,which reduces the surface potential and makes the electron implantation difficult.Therefore,the PCE of MAPbI3-based planar PSCs decreased in different degrees,and the hysteresis was more serious.However,after NHx+and CHx+ion beams implanted,the PCE of the PSCs devices based on(TiO2)DC-PMS ETL decreased less than of PSCs devices based on(TiO2)Sol-gelETL.This is because(TiO2)DC-PMS ETL contains the fiber like structure throughout the ETL,which inhibits the implantation of NHx+and CHx+ion beams.Therefore,PSCs devices based on NH+ and CHx+ion beam implanted(TiO2)DC-PMSETL shows better service stability. |
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